The thickness of liquid crystal display devices can be reduced, and power consumption of the liquid crystal display devices is low. Thus, the liquid crystal display devices have been broadly used as displays for OA equipment such as television sets and personal computers, mobile electronic devices such as mobile phones and smartphones, and cockpits of automobiles and aircrafts.
The liquid crystal display device includes a display panel and a backlight unit attached to a rear side of the display panel. The display panel has such a configuration that an array substrate and a counter substrate disposed so as to face the array substrate are bonded together with a sealant, and a liquid crystal material is sealed in the space between both substrates. A substrate slightly smaller than the array substrate is used as the counter substrate, and a drive circuit is, using a system on film (SOF) or tape automated bonding (TAB), mounted on terminals of the array substrate exposed by the foregoing size difference.
The display panel has a display region where an image is displayed and a non-display region surrounding the display region. In the display region, a plurality of pixels are arranged in a matrix. A switching element such as a thin film transistor and a pixel electrode connected to the switching element are provided corresponding to each pixel on the array substrate. Moreover, a common electrode is provided so as to cover at least the entirety of the display region of the counter substrate. Current flows through each pixel electrode in synchronization with ON/OFF of an associated one of the switching elements. The common electrode is electrically connected to common transition electrodes provided on the array substrate, a common potential is applied from a common transition electrode lead line to the common electrode through each common transition electrode.
An alignment film is, on the surface of the array substrate contacting a liquid crystal layer, formed so as to cover at least the display region. Similarly, an alignment film is, on the surface of the counter substrate contacting the liquid crystal layer, formed so as to cover at least the display region.
The alignment film can be formed in such a manner that a resin film formed using, e.g., flexographic printing or an ink-jet method and made of, e.g., polyimide is subjected to rubbing or photo-alignment. The ink-jet method is preferably used for formation of the resin film such as a polyimide film because of the following excellent characteristics: a solution can be directly applied to the substrate; a low contamination can be achieved because of the ink-jet method being a non-contact process; a solution consumption amount is low; and a process time can be shortened.
In the case of forming the alignment film by the ink-jet method, resin having a lower viscosity than that used in the case of the flexographic printing is used as a raw material of the alignment film, and therefore, it is likely that the raw material of the alignment film leaks out to the region around the region (display region) targeted for printing. Thus, if the non-display region around the display region is small and a large clearance between the display region and the sealant region cannot be ensured, the alignment film spreads out to the sealant region. In this case, the liquid crystal material of the liquid crystal layer cannot be completely sealed due to insufficient adhesion between the sealant and the alignment film, resulting in leakage of the liquid crystal material of the liquid crystal layer.
In order to solve the foregoing problem, Patent Document 1 discloses a liquid crystal display device configured such that grooves extending along the outer periphery of a display region are formed in a substantially-circular region outside the display region and inside the region where a sealant is applied. According to such a configuration, even if a liquid resin material applied using the ink-jet method spreads outward of the display region, the grooves can prevent spreading of the resin material, and spreading-out and leakage of an alignment film on the outside of the display region can be reduced. Patent Document 1 further discloses the configuration in which a conductive film such as an ITO film is formed on the surfaces of the grooves. Since the liquid resin material, i.e., an alignment film material, has a low wettability to the ITO film, the foregoing configuration can prevent spreading-out and leakage of the liquid resin material from the grooves.